use std::old_io::{fs, IoResult};
use std::old_path::GenericPath;
use std::old_path::posix::Path;
use file::{File, GREY};

#[cfg(feature="git")] use ansi_term::{ANSIString, ANSIStrings};
#[cfg(feature="git")] use ansi_term::Colour::*;
#[cfg(feature="git")] use git2;

/// A **Dir** provides a cached list of the file paths in a directory that's
/// being listed.
///
/// This object gets passed to the Files themselves, in order for them to
/// check the existence of surrounding files, then highlight themselves
/// accordingly. (See `File#get_source_files`)
pub struct Dir {
    contents: Vec<Path>,
    path: Path,
    git: Option<Git>,
}

impl Dir {
    /// Create a new Dir object filled with all the files in the directory
    /// pointed to by the given path. Fails if the directory can't be read, or
    /// isn't actually a directory.
    pub fn readdir(path: &Path) -> IoResult<Dir> {
        fs::readdir(path).map(|paths| Dir {
            contents: paths,
            path: path.clone(),
            git: Git::scan(path).ok(),
        })
    }

    /// Produce a vector of File objects from an initialised directory,
    /// printing out an error if any of the Files fail to be created.
    ///
    /// Passing in `recurse` means that any directories will be scanned for
    /// their contents, as well.
    pub fn files(&self, recurse: bool) -> Vec<File> {
        let mut files = vec![];

        for path in self.contents.iter() {
            match File::from_path(path, Some(self), recurse) {
                Ok(file) => files.push(file),
                Err(e)   => println!("{}: {}", path.display(), e),
            }
        }

        files
    }

    /// Whether this directory contains a file with the given path.
    pub fn contains(&self, path: &Path) -> bool {
        self.contents.contains(path)
    }

    /// Append a path onto the path specified by this directory.
    pub fn join(&self, child: Path) -> Path {
        self.path.join(child)
    }

    /// Return whether there's a Git repository on or above this directory.
    pub fn has_git_repo(&self) -> bool {
        self.git.is_some()
    }

    /// Get a string describing the Git status of the given file.
    pub fn git_status(&self, path: &Path, prefix_lookup: bool) -> String {
        match (&self.git, prefix_lookup) {
            (&Some(ref git), false) => git.status(path),
            (&Some(ref git), true)  => git.dir_status(path),
            (&None, _)              => GREY.paint("--").to_string(),
        }
    }
}

/// Container of Git statuses for all the files in this folder's Git repository.
#[cfg(feature="git")]
struct Git {
    statuses: Vec<(Path, git2::Status)>,
}

#[cfg(feature="git")]
impl Git {

    /// Discover a Git repository on or above this directory, scanning it for
    /// the files' statuses if one is found.
    fn scan(path: &Path) -> Result<Git, git2::Error> {
        use std::os::unix::ffi::OsStrExt;
        use std::ffi::AsOsStr;

        // TODO: libgit2-rs uses the new Path module, but exa still uses the
        // old_path one, and will have to continue to do so until the new IO
        // module gets a bit more developed. So we have to turn Paths into
        // old_path::Paths. Yes, this is hacky, but hopefully temporary.
        let repo = try!(git2::Repository::discover(path));
        let workdir = match repo.workdir() {
            Some(w) => Path::new(w.as_os_str().as_bytes()),
            None => return Ok(Git { statuses: vec![] }),  // bare repo
        };

        let statuses = try!(repo.statuses(None)).iter()
                                                .map(|e| (workdir.join(e.path_bytes()), e.status()))
                                                .collect();
        Ok(Git { statuses: statuses })
    }

    /// Get the status for the file at the given path, if present.
    fn status(&self, path: &Path) -> String {
        let status = self.statuses.iter()
                                  .find(|p| &p.0 == path);
        match status {
            Some(&(_, s)) => ANSIStrings( &[Git::index_status(s), Git::working_tree_status(s) ]).to_string(),
            None => GREY.paint("--").to_string(),
        }
    }

    /// Get the combined status for all the files whose paths begin with the
    /// path that gets passed in. This is used for getting the status of
    /// directories, which don't really have an 'official' status.
    fn dir_status(&self, dir: &Path) -> String {
        let s = self.statuses.iter()
                             .filter(|p| dir.is_ancestor_of(&p.0))
                             .fold(git2::Status::empty(), |a, b| a | b.1);

        ANSIStrings( &[Git::index_status(s), Git::working_tree_status(s)] ).to_string()
    }

    /// The character to display if the file has been modified, but not staged.
    fn working_tree_status(status: git2::Status) -> ANSIString<'static> {
        match status {
            s if s.contains(git2::STATUS_WT_NEW) => Green.paint("A"),
            s if s.contains(git2::STATUS_WT_MODIFIED) => Blue.paint("M"),
            s if s.contains(git2::STATUS_WT_DELETED) => Red.paint("D"),
            s if s.contains(git2::STATUS_WT_RENAMED) => Yellow.paint("R"),
            s if s.contains(git2::STATUS_WT_TYPECHANGE) => Purple.paint("T"),
            _ => GREY.paint("-"),
        }
    }

    /// The character to display if the file has been modified, and the change
    /// has been staged.
    fn index_status(status: git2::Status) -> ANSIString<'static> {
        match status {
            s if s.contains(git2::STATUS_INDEX_NEW) => Green.paint("A"),
            s if s.contains(git2::STATUS_INDEX_MODIFIED) => Blue.paint("M"),
            s if s.contains(git2::STATUS_INDEX_DELETED) => Red.paint("D"),
            s if s.contains(git2::STATUS_INDEX_RENAMED) => Yellow.paint("R"),
            s if s.contains(git2::STATUS_INDEX_TYPECHANGE) => Purple.paint("T"),
            _ => GREY.paint("-"),
        }
    }
}

#[cfg(not(feature="git"))]
struct Git;

#[cfg(not(feature="git"))]
impl Git {
    fn scan(_: &Path) -> Result<Git, ()> {
        // Don't do anything without Git support
        Err(())
    }

    fn status(&self, _: &Path) -> String {
        // The Err above means that this should never happen
        panic!("Tried to access a Git repo without Git support!");
    }

    fn dir_status(&self, path: &Path) -> String {
        self.status(path)
    }
}